Modern computer systems feature powerful digital processor integrated circuit devices. The processors are used to execute software instructions that implement complex functions, such as, for example, real-time 3-D graphics applications, photo-retouching and photo editing, data visualization, and the like. The performance of many these graphics-reliant applications is directly benefited by more powerful graphics processors which are capable of accurately displaying large color depths (e.g., 32 bits, etc.), high resolutions (e.g., 1900×1200, 2048×1536 etc.), and are thus able to more clearly present visualized information and data to the user. Computer systems configured for such applications are typically equipped with high-quality, high-resolution displays (e.g., high-resolution CRTs, large high-resolution LCDs, etc.). Video quality generated by the computer system's graphics subsystem and display becomes a primary factor determining the computer system's suitability.
The graphics subsystem of a computer system typically comprises those electronic components that generate the video signal sent through a cable to a display. In modern computers, the graphics subsystem comprises a graphics processor unit (GPU) that is usually mounted on the computer's motherboard or on an expansion board (e.g., discrete graphics card) plugged into the motherboard. The GPU is electrically coupled to a video connector which is in turn used to couple signals from the GPU to the display. In those cases where the GPU is mounted directly on the motherboard, the connector is also mounted on the motherboard. In those cases where the adapter is a discrete add-in graphics card, the connector is mounted on the graphics card.
The connector for coupling the computer system to the display is typically a VGA type connector or a DVI type connector. The vast majority of the connectors produced in the past have traditionally been VGA (Video Graphics Array) type connectors. VGA connectors refer to the original analog graphics physical interconnect standard introduced with the industry standard IBM PS/2 series. A majority of displays available in the marketplace are compatible with VGA type connectors. More recently, an increasing number of high-quality displays are compatible with DVI (Digital Visual Interface) type connectors. DVI refers to a digital interface standard created by the Digital Display Working Group (DDWG) to convert analog signals into digital signals to accommodate both analog and digital monitors. Generally, digital DVI signals are capable of providing higher fidelity, higher quality images than the analog VGA signals.
Digital DVI was specifically configured to maximize the visual quality of flat panel LCD monitors and to realize the performance potential of high-end graphics cards. DVI is becoming increasingly popular with video card manufacturers, and many recent graphics cards available in the marketplace now include both a VGA and a DVI output port. In addition to being used as the new computer interface, DVI is also becoming the digital interconnect method of choice for HDTV, EDTV, Plasma Display, and other ultra-high-end video displays for TV, movies, and DVDs. Likewise, even a few of the top-end DVD players are now featuring DVI outputs.
A problem exists however with respect to the fact that the great majority of the displays existing in the installed base (e.g., the displays that have been purchased within the past 10 years and are still in use) are not compatible with digital DVI. There are three types of DVI connections: DVI-D (Digital); DVI-A (Analog); and DVI-I (Integrated Digital/Analog). The DVI-D format is used for direct digital connections between source video (namely, graphics cards) and digital LCDs (or rare CRT) monitors. This provides a faster, higher-quality image than with analog VGA, due to the nature of the digital format. The DVI-A format is used to carry a DVI signal to an analog display, such as a CRT monitor or an HDTV. Although some signal quality is lost from the digital to analog conversion, it still transmits a higher quality picture than standard VGA. The DVI-I format is an integrated cable which is capable of transmitting either a digital-to-digital signal or an analog-to-analog signal. The DVI-I connectors and cables can support both analog displays and digital displays, and has thus become a preferred connector. But the great majority of the displays in the installed base cannot natively accept a DVI-I cable.
One prior art solution to this problem involved the development of DVI-I to VGA adapter components that are configured to convert the analog signals from the DVI-I format to the VGA format. These adapters often come in the form of a “dongle” or component that hangs off on the back of the computer system and is connected in-series between the graphics card of the computer system and the analog display. One connector of the dongle is designed to mate with a DVI-I connector and the other end of the dongle is designed to mate with a VGA connector. This enables a digital output computer to use a VGA display.
This solution is less than satisfactory due to the fact that the prior art dongles require intricate internal wiring and soldering in order to physically couple the signal lines for the analog DVI-I signal to the VGA signal. The internal wiring requires precise control with respect to wire length and wire impedance in order to maintain high signal quality for high-quality displays. The internal wiring requires proper EMI shielding to prevent EMI (electromagnetic interference) problems. These requirements make proper quality control of the often labor-intensive manufacturing processes for the prior art type dongle difficult. Low-cost manufacturing techniques often yield sub-par components. High-quality components can only be obtained (if at all) at a high cost. Thus a need exists for a high-quality, readily manufacturable conversion device compatible VGA connectors and with more advanced digital connections such as DVI-I.